The story

A steady stream of superdelegate endorsements on Tuesday pushed Sen. Barack Obama over the threshold to lay claim to the Democratic presidential nomination.

As the polls closed in South Dakota on Tuesday, which along with Montana is one of two states holding the last Democratic nominating contests, CNN estimated that Obama had gathered the 2,118 delegates needed to capture the nomination.

Obama began the day 42 delegates short of being able to claim the nomination and an allocation of the 31 up for grabs in South Dakota and Montana wouldn't have been enough to clinch.

But all through the day Tuesday, announcements began to float from some of the 193 superdelegates who began the day uncommitted to either Obama or Sen. Hillary Clinton.

Among those declaring their support for Obama on Tuesday were former President Jimmy Carter Rep. James Clyburn, the top African-American in Congress. Read full article »